It's not the first time he's waded into the debate. "To think that Apple won't allow us to get into [the] cell phone," Trump said two days earlier on "Fox and Friends." "Who do they think they are?"

The FBI wants Apple to help it break into a smartphone used by Syed Rizwan Farook, who along with his wife, killed 14 people in San Bernardino, California, on Dec. 2. FBI Director James Comey has said the shooters were inspired by "foreign terrorist organizations."

The FBI says it needs access to the data to fully investigate the attack and find any possible collaborators. Apple has resisted, saying the move would set a dangerous precedent and compromise security for all its customers.

"Once created, the technique could be used over and over again, on any number of devices," CEO Tim Cook said in an open letter Monday.

It's unknown if Trump's supporters will heed his suggestion. The outspoken businessman and television personality has already tussled with the Pope this week after the religious leader suggested Trump is "not a Christian."